Rake receiver for spread spectrum signal demodulation

ABSTRACT

The architecture of the present invention is premised upon an algorithm involving integration of oblique correlators and RAKE filtering to null interference from other spread spectrum signals. The oblique correlator is, of course, based on the non-orthogonal projections that are optimum for nulling structured signals such as spread spectrum signals. RAKE filtering is used to rapidly steer the beam of the multi-antenna system and to mitigate the effects of multipath.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 08/916,884, filed Aug. 22, 1997, of the same title which,claims priority from U.S. Provisional Application entitled “PHASED-RAKERECEIVER FOR SIGNAL DEMODULATION”, having Ser. No. 60/024,525 and filedAug. 23, 1996, which is incorporated fully herein by reference.

FIELD OF THE INVENTION

The present invention is generally directed to a system for receiving aspread spectrum signal and specifically to a system for receiving anddemodulating a spread spectrum signal.

BACKGROUND OF THE INVENTION

Spread spectrum techniques are finding larger roles in a variety ofapplications. In cellular telephony, spread spectrum based systems offerthe potential for increased efficiency in the use of bandwidth. Theresistance of spread spectrum methods to jamming make them ideallysuited for radar and Global Positioning System (GPS) applications. Forradar applications, spread spectrum signals have a lower probability ofbeing intercepted due to the noise-like appearance of spread spectrumwaveforms. In addition, it may be used to increase the pulse repetitionfrequency without sacrificing unambiguous range.

In spread spectrum radars, GPS, and cellular telephony applications(e.g., Code Division Multiple Access (CDMA)), each transmitted signal orpulse is assigned a time varying pseudo-random code that is used tospread each bit in the digital data stream (i.e., an interference code),such as the long code and PN code in CDMA applications. In CDMAapplications, this spreading causes the signal to occupy the entirespectral band allocated to the Multiple Access System (MAS). Thedifferent users in such a system are distinguished by uniqueinterference codes assigned to each. Accordingly, all userssimultaneously use all of the bandwidth all of the time and thus thereis efficient utilization of bandwidth resources. In addition, sincesignals are wide-band, the multipath delays can be estimated andcompensated for. Finally, by carefully constructing interference codes,base stations can operate with limited interference from adjacent basestations and therefore operate with higher reuse factors (i.e., more ofthe available channels can be used).

In spread spectrum systems, all other spread spectrum signals contributeto background noise, or interference, relative to a selected spreadspectrum signal. Because each user (or radar pulse or GPS satellitesignal) uses a noise-like interference code to spread the bits in asignal, all the users contribute to the background noise. In CDMAsystems in particular, user generated background noise, while having aminimal effect on the forward link (base-to-mobile) (due to thesynchronized use of orthogonal Walsh Codes), has a significant effect onthe reverse link (mobile to base)(where the Walsh Codes are commonly notsynchronized and therefore nonorthogonal). The number of users abase-station can support is directly related to the gain of the antennaand inversely related to the interference. Gain is realized through theamplification of the signal from users that are in the main beam of theantenna, thereby increasing the detection probability in thedemodulator. Interference decreases the probability of detection for asignal from a given user. Although “code” filters are used to isolateselected users, filter leakage results in the leakage of signals ofother users into the signal of the selected user, thereby producinginterference. This leakage problem is particularly significant when theselected user is far away (and thus the user's signal is weak) and theinterfering user is nearby (and thus the interfering user's signal isstrong). This problem is known as the near-far problem.

There are numerous techniques for improving the signal-to-noise ratio ofspectrum signals where the noise in the signal is primarily a result ofinterference caused by other spread spectrum signals. These techniquesprimarily attempt to reduce or eliminate the interference by differentmechanisms.

In one technique, the interfering signals are reduced by switchingfrequency intervals assigned to users. This technique is useless for theintentional jamming scenario in which jammers track the transmitterfrequencies. Frequency switching is not an option for the CDMA standardfor cellular telephones. In that technology, all users use all of thefrequencies at all times. As a result there are no vacant frequencybands to switch to. In another technique, the interfering signals areselectively nulled by beam steering. Classical beam steering, however,does not provide, without additional improvements, the required angularresolution for densely populated communications environments.

The above techniques are further hampered due to the fact that signalsrarely travel a straight line from the transmitter to the receiver. Infact, signals typically bounce off of buildings, trees, cars, etc., andarrive at the receiver from multiple directions. This situation isreferred to as the multipath effect from the multiple paths that thevarious reflections that a signal takes to arrive at the receiver.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a systemarchitecture for increasing the signal-to-noise ratio (SNR) of a spreadspectrum signal. Another objective is to provide a system architecturefor removing the interference from a spread spectrum signal,particularly the interference attributable to spread spectrum signalsgenerated by other sources. Yet another objective is to provide a systemarchitecture for removing the interference from a spread spectrum signalthat does not employ beam steering. Specific related objectives includeproviding a demodulating/decoding system for efficientlydemodulating/decoding spread spectrum signals generated by far awaysources in the presence of spread spectrum signals generated by nearsources and/or effectively accounting for the various multipaths of aspread spectrum signal.

These and other objectives are addressed by the spread spectrum systemarchitecture of the present invention. In a first configuration of thepresent invention, the system includes: (i) an antenna adapted toreceive a signal that is decomposable into a first signal segment and asecond signal segment, the first signal segment of the signal beingattributable to a first source and the second signal segment of thesignal being attributable to a source other than the first source; and(ii) an oblique projecting device, in communication with the antenna,for determining the first signal segment. The signal can be anystructured signal, such as a spread spectrum signal. A “structuredsignal” is a signal that has known values or is created as a combinationof signals of known values.

The oblique projecting device determines the first signal segment byobliquely projecting a signal space spanned by the signal onto a firstspace spanned by the first signal segment. As used herein, the “space”spanned by a set “A” of signals is the set of all signals that can becreated by linear combinations of the signals in the set “A”. Forexample, in spread spectrum applications, the space spanned by thesignals in set “A” are defined by the interference codes of the one ormore selected signals in the set. Thus the space spanned by interferingsignals is defined by all linear combinations of the interferingsignals. The signal space can be obliquely projected onto the axis alonga second space spanned by the second signal segment. The estimatedparameters of the first signal segment are related to the actualparameters of the first signal segment and are substantially free ofcontributions by the second signal segment. Through the use of obliqueprojection, there is little, if any, leakage of the second signalsegment into computed parameters representative of the first signalsegment.

For spread spectrum applications where noise characteristics arequantifiable, oblique projection is preferably performed utilizing thefollowing algorithm:

(I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I—S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H^(T)(I−S(S ^(T) S)−1 S ^(T))

and hypothetical correlation functions generated using the followingequation:

(y^(T)(I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T))H)⁻¹ H^(T)(I−S(S ^(T) S)⁻¹ S ^(T))y)/σ²

where y corresponds to a selected portion of the spread spectrum signal,H corresponds to an interference code matrix for the first signalsegment (which defines a first space including the first signal), Scorresponds to the interference code matrices for signals of all of theother sources (users) in the selected portion of the spread spectrumsignal (which defines a second space including the signals of the othersources), ^(T) corresponds to the transpose operation, I is the identitymatrix, and σ² corresponds to the variance of the magnitude of the noisein the selected portion of the spread spectrum signal. Where noise ispresent, a substantial portion of the noise may be generated by thereceiver:

(y ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H^(T)(I−S(S ^(T) S)⁻¹ S ^(T))y)/σ²

The system can have a number of advantages, especially in spreadspectrum systems. The system can significantly increase thesignal-to-noise ratio (SNR) of the spread spectrum signal relative toconventional spread spectrum demodulating systems, thereby increasingthe detection probability. This is realized by the almost completeremoval (i.e., nulling) from the spread spectrum signal of interferenceattributable to spread spectrum signals generated by other sources.Non-orthogonal (oblique) projections are optimum for nulling structuredsignals such as spread spectrum signals. In CDMA systems, the system canefficiently demodulate/decode spread spectrum signals generated by faraway (weak) sources in the presence of spread spectrum signals generatedby near (strong) sources, thereby permitting the base station for agiven level of signal quality to service more users and operate moreefficiently. An improvement in SNR further translates into an increasein the user capacity of a spectral bandwidth—which is a scarce resource.Unlike conventional systems, the system does not require beam steeringto remove the interference.

In applications where the first signal includes a number of multipathsignal segments, the system can include a threshold detecting device, incommunication with the oblique projecting device, for generating timinginformation defining a temporal relationship among the plurality ofmultipath signal segments (e.g., using mathematical peak locationtechniques that find the points at which the slope of the surfacechanges from positive to negative and has a large magnitude) and atiming reconciliation device for determining a reference time based onthe timing information (i.e., the multipath delays). Multipath signalsegments correspond to the various multipaths followed by a signal(e.g., the first signal) after transmission by the signal source.

The system can include a RAKE processor in communication with theoblique projecting device and the timing reconciliation device foraligning the plurality of multipath signal segments in at least one oftime and phase and/or scaling the magnitude(s) of the multipath signalsegments. RAKE processing rapidly steers the beam of a multi-antennasystem as well as mitigates multipath effects. The RAKE processorpreferably aligns and scales using the following algorithm:${y_{R}(K)} = {\frac{1}{\sum\limits_{i = 1}^{p}A_{i}}{\sum\limits_{i = 1}^{p}{A_{i}^{{- {j\varphi}}\quad i}{y\left( {k + t_{i}} \right)}}}}$

where p is the number of the multipath signal segments (or peaks); i isthe number of the multipath signal segment; A_(i) is the amplitude ofith multipath signal segment; j is the amount of the phase shift; φ_(i)is the phase of the ith multipath signal segment; y(k) is the inputsequence; and t_(i) is the delay in the received time for the ithmultipath signal segment.

The RAKE processor effectively focuses the beam on the desired signalsource. The oblique projecting device and RAKE processor null out thesignals of other sources in the spread spectrum signal and therebyeliminate the need for null steering to be performed by the antenna. Thesystem of the present invention is less complex and more efficient thanconventional beam steering systems.

The system can include a demodulating device in communication with theRAKE processor to demodulate each of the signal segments. Like theoblique projecting device, the demodulating device uses the equationnoted above with respect to the oblique projecting device. Unlike theoblique projecting device which uses portions of the filtered signal toperform oblique projection, the demodulating device uses the output ofthe RAKE processor which has aligned and summed all of the multipathsignal segments. Both the oblique projecting and demodulating devicesuse estimates of the transmission time (“trial time”) and symbol(“candidate symbol”) and the receive time in determining a correlationfunction using the above equation. “Receive time” is the index into thereceived data stream (or spread spectrum signal) and represents the timeat which the data (or spread spectrum signal) was received by theantenna. “Transmission time” is the time at which the source transmitteda selected portion of the data stream (i.e., the selected signal).

In another configuration, the system includes a plurality of antennas(i.e., an antenna array), with each antenna having a respective obliqueprojecting device, threshold detecting device, and RAKE processor. Acommon timing reconciliation device is in communication with each of therespective threshold detecting devices and RAKE processors. A commondemodulating component is also in communication with each of the RAKEprocessors. In this configuration, the demodulating component sums allof the first signals received by each of the antennas to yield acorrected first signal reflecting all of the various multipath signalsegments related to the first signal.

In either configuration, the system can effectively accommodate thevarious multipath signal segments related to a source signal. The RAKEprocessor weights each of the multipath signal segments in directrelation to the magnitude of the peak defined by each multipath signalsegment.

The above description of the configurations of the present invention isneither complete nor exhaustive. As will be appreciated, otherconfigurations are possible using one or more of the features set forthabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a first embodiment of the present invention;

FIG. 2 depicts the various components of the correlating device;

FIG. 3 depicts the unit steps performed by the components of FIG. 2;

FIG. 4 depicts graphically the oblique projecting operation;

FIG. 5 depicts the signal segments contained in a portion of thefiltered signal;

FIG. 6 depicts the three dimensional correlation surface output by thebank of projection filters in the correlating device in FIG. 1;

FIG. 7 pictorially depicts the operation of the RAKE processor;

FIG. 8 depicts the various components of the demodulating device;

FIG.9 depicts a correlation surface defined by the correlation functionoutput by the output by the bank of projection filters in thedemodulating device of FIG. 1;

FIG. 10 is a second embodiment of the present invention for an antenna,array;

FIG. 11 is the first part of a flow schematic of the software foroperating the system of FIG. 10; and

FIG. 12 is the second part of the flow schematic.

DETAILED DESCRIPTION

The present invention provides a software architecture and theunderlying mathematical algorithms for demodulating/decodingcommunications signals containing interference noise. This invention isgenerally applicable to CDMA systems (and other spread spectrumsystems), Frequency Division Multiple Access systems (FDMA) and TimeDivision Multiple Access systems (TDMA) and particularly for spreadspectrum systems, such as CDMA. In spread spectrum systems, interferencenoise is typically due to a dense population of signals using the sameintervals of the frequency spectrum, such as in high user densitycellular phone applications, or such as in the intentional interferenceof radar or communication signals by nearby jammers.

Single Antenna Systems

An overview of the current architecture for detecting signals from anith user in a CDMA system is illustrated in FIG. 1. The architectureemploys a single antenna for receiving CDMA signals. The system includesthe antenna 50 adapted to receive the spread spectrum signal andgenerate an output signal 54, filters 58 and 60 for filtering thein-phase (“I”) and quadrature (“Q”) channels to form filtered channelsignals 62 and 66, a correlating device 70 for providing a hypotheticalcorrelation function characterizing a filtered signal segment, which maybe multipath signal segment(s) of a source signal (hereinaftercollectively referred to as a “signal segment”), transmitted by aselected user, a first threshold detecting device 74 for generatingtiming information defining the temporal relationship among a pluralityof peaks defined by the hypothetical correlation function, a timingreconciliation device 78 for determining a reference time based on thetiming information, a RAKE processor 82 for aligning multipath signalsegments for each selected user in time and phase and outputting analigned signal for the selected user, a demodulating device 86 fordemodulating aligned signals transmitted by each selected user intocorrelation functions and, finally, a second threshold detecting device90 for converting the correlation functions into digital information. Aswill be appreciated, a system configured for radar or GPS applicationswill not include some of these components, such as the filters 58 and60.

The antenna can be of any suitable configuration for receiving astructured signal and providing the output signal based thereon, such asan antenna having one or a number of antenna elements. As will beappreciated, the output signal is a mix of a plurality of signalsegments transmitted by a number of mobile units (or users). The outputsignal is coherently shifted down from radio frequency and split into anin-phase (I) channel and a quadrature (Q) channel.

The I and Q channels of the output signal are filtered by the filters,H*(f), designated as 58 and 60, to form the filtered signals 62 and 66.Filtered signal 62 corresponds to the I channel of the output signalwhile filtered signal 66 corresponds to the Q channel. The filters 58and 60 are counterparts to the filter H(f) applied at the mobile unit tocontain the transmitted signal within the specified bandwidth.

Referring to FIGS. 1-3, the correlating device 70 includes a user codegenerator 94, a projection builder 98, and a bank of projection filters102. For each of the filtered signals 62 and 66, the user code generator94 selects 106 a user (i.e., the selected user) transmitting a selectedsignal segment in a selected portion of the filtered signal to bedecoded, selects 110, for the selected user and signal segment, a set oftrial transmit times (“trial times”) and candidate symbols and, for eachtrial time and candidate symbol in the set, generates 114 a candidateuser code (or interface code) for the selected user and signal segment.In selecting trial times, the base-station is assumed to haveapproximate synchronization with each of the mobile units. Using thisapproximate synchronization, the base station has a set of trial timesat which each selected mobile unit may have transmitted the selectedsignal segment included in the filtered signals 62 and 66. For eachtrial time, t_(p), in the set of trial times for the selected user andsignal segment, the user code generator 94 generates one or morecandidate user codes indexed by trial time and candidate symbol. The setof trial times used by the user code generator for determining the setof candidate user codes for a given signal segment is determined byknown techniques. Typically, the user code generator will use a timeinterval centered on the receive time for the signal segment that has awidth of about 200 milliseconds or less and more typically of about 50milliseconds or less. These steps are repeated for each of the activeusers transmitting signal segment(s) of the filtered signal.

The projection builder 98 selects 118 a portion of the filtered signalto process, collects 122 appropriate candidate user codes for the userstransmitting signal segments of the selected filtered signal portionfrom the output of the user code generator, and, using the receive timeoffsets, trial times, and candidate symbols, creates 126 a set ofhypothetical projection operators.

The hypothetical projection operators are generated using the algorithm:

(I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H^(T)(I−S(S ^(T) S)⁻¹ S ^(T))

where H corresponds to an interference code matrix for the selectedsignal segment, S corresponds to the interference code matrices for allof the other signal segments in the selected filtered signal portion, Iis the identity matrix, and ^(T) corresponds to the transpose operation.The variables H and S depend upon the interference codes determined bythe user code generator 94. Accordingly, H and S depend, respectively,upon the transmit time for the selected signal segment, and the transmittimes of all of the other signal segments in the selected filteredsignal portion. Because the data is indexed by the receive time, S isalso a function of the receive time:

(I−S(S ^(T) S) ⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T))H)⁻¹ H^(T)(I−S(S ^(T) S) ⁻¹S^(T)).

To apply the above-equation, the projection builder 98 estimates thetransmit times and symbols of each of the signal segments in theselected filtered signal portion. As noted, the trial time is anestimate of the transmit time and the candidate symbol of the symbol.

Next, the bank of projection filters 102, with one filter correspondingto each trial time and candidate symbol (i.e., to each hypotheticalprojection operator), provide a set of filter outputs (i.e.,hypothetical correlation functions) to be threshold detected by thefirst threshold detecting device 74. Each of the bank of projectionfilters correlates 130 a plurality of multipath signal segments for agiven trial time and candidate symbol. The projection filters 102extract an estimated signal segment attributable to a given user fromeach selected filtered signal portion while simultaneously nulling outthe other signal segments from other-users.

The equation used to generate the various hypothetical correlationfunctions is:

(y^(T)) (projection operator for selected signal portion)(y)/σ²

where y corresponds to the selected filtered signal portion 62 or 66 andσ² corresponds to the variance of the magnitude of the noise portioncontained in the respective filtered signal portion. The equation isbased on oblique or non-orthogonal projections of y onto space spannedby H to null interference (i.e., interference from signal segmentstransmitted by other users) and yield the signal segment transmitted bythe selected user. Because the receive times for the various signalsegments of a selected user are unknown, a number of signal segments ofthe user, each at a different receive-time offset, must be correlated bythe bank of projection filters.

The oblique projection of y space 134 spanned by y onto H space 138spanned by H to yield an estimate of the signal segment 142 isillustrated in FIG. 4. Y space 134 spanned by Y is obliquely projectedonto the H space 138 along S space 146 spanned by S. Oblique projectionsare more effective than orthogonal projections in removing interferenceattributable to the other users where the Walsh codes are notsynchronized and thus not orthogonal, such as in the reverse link of aCDMA system. In such cases, the correlation function is independent ofthe amplitudes of the signal segments of other users and, therefore,power control of the transmitter is not a significant consideration.

By way of illustration, FIG. 5 illustrates a four (4) user system inwhich the various users are transmitting symbols representing bits ofdata. The source signals are received by the antenna 50 as a number ofmultipath signal segments. A first multipath signal segment 150 istransmitted by a first user, a second multipath signal segment 154 by asecond user, a third multipath signal segment 158 by a third user, afourth multipath signal segment 162 by the first user, and a fifthmultipath signal segment 166 from a fourth user. The projection builder98 selects a first receive time offset Δt₁ and thereby selects thefirst, second and third multipath signal segments 150, 154 and 158. Thewidth of the receive time offset is determined by the control system forthe base station using known techniques. For the first multipath signalsegment 150, the projection builder 98 employs Δt₁ and a trial time andcandidate symbol in the projection operator equation and generates ahypothetical projection operator for the first user indexed by the trialtime and candidate symbol. For the second multipath signal segment 154,the projection builder employs Δt₁, and a trial time and candidatesymbol in the projection operator equation and generates a hypotheticalprojection operator for second user indexed by the trial time andcandidate symbol. This operation is also performed for the thirdmultipath signal segment 158 with a hypothetical projection operator forthe third user being likewise generated. For the second receive timeoffset, Δt₂, the projection builder repeats the above steps for each ofthe fourth and fifth multipath signal segments 162 and 166 to generateadditional projection operators for the first and fourth users. Althoughthe first and fourth miltipath signals are multipaths of a common sourcesignal, the hypothetical projection operators for the first and fourthmultipath signal segments are different due to differing degrees ofinterference. These steps are repeated for subsequent receive timeoffsets. The number of receive time offsets generated is determined bythe base station control system using known techniques. The bank ofprojection filters 102 then apply each of the hypothetical projectionoperators to the filtered signal portion corresponding to the respectivereceive time offset to develop a plurality of hypothetical correlationfunctions for the various users. Each of the hypothetical correlationfunctions defines a correlation surface 170 of the type depicted in FIG.6, where the horizontal axes represent receive time and trial time andthe vertical axis represents the output of the correlation function fora specific pair of receive times and trial times. One correlationfunction corresponds to a source signal transmitted by the selecteduser. Each peak 174 a-d represents a multipath signal segment of thesource signal.

The first threshold detecting device 74 uses the hypotheticalcorrelation functions for each user that are outputted by the bank ofprojection filters 102 to determine the temporal locations of thevarious multipath signal segments in the hypothetical correlationfunction. Due to multipath delays, each hypothetical correlationfunction can have multiple peaks as shown in FIG. 6. As set forth above,the various peaks in the correlation surface can be isolated using knownmathematical techniques. Using techniques known in the art and thetemporal location of the peaks (or timing information) output by thefirst threshold detecting device 74, the timing reconciliation device 78determines a reference time for the RAKE processor 82. The referencetime is based upon the receive times of the various peaks located by thefirst threshold detecting device 74. The reference time is used by theRAKE processor 82 as the time to which all of the signal segments for agiven user are aligned.

The RAKE processor 82 based on the timing information, the peakamplitudes of the hypothetical correlation function(s) detected by thefirst threshold detecting device, and the filtered signals 62 and 66scales and aligns (in time and phase) the various multipath signalsegments. transmitted by a given user and then sums the aligned signalsegments for that user. The RAKE processor 82 can be a maximal SNRcombiner.

The operation of the RAKE processor is illustrated in FIG. 7 (for anantenna array). As noted, the output of the bank of projection filtersis the hypothetical correlation function, which in multipathenvironments typically has multiple peaks. Assuming that there are pmultipaths or signal segments and therefore p peaks, the RAKE processdetermines the amplitudes, {A_(i)}^(p) _(i=1), time delays, {t}^(p)_(i,i=1), and phase delays {ø_(i)}^(p) _(i=1). If y(k) is a sequencedefining the filtered signal 62 or 66, then the “RAKED” sequence isy_(R)(K)${y_{R}(K)} = {\frac{1}{\sum\limits_{i = 1}^{p}A_{i}}{\sum\limits_{i = 1}^{p}{A_{i}^{{- {j\varphi}}\quad i}{y\left( {k + t_{i}} \right)}}}}$

Referring again to FIGS. 1 and 7 (which illustrates the operation ofRAKE processor 82), the RAKE processor 82 first sums 178 the outputs ofthe various antenna elements, shifts 182 the various sequences in theoutputs by the amounts of the multipath delays between the correspondingmultipath signal segments of a selected signal segment, so that allmultipath signal segments are perfectly aligned. It then weights eachshifted multipath signal segment by the amplitude of the correlationfunction corresponding to that segment and sums 186 the weightedcomponents to produce the aligned signal y_(R)(k). The aligned signaly_(R)(k) is then detected 187 to form digital output 188.

The demodulating device 86 correlates the “RAKED” sequence, y_(R)(k)with the appropriate replicated segment of the coded signal in thefilter bank 102 to produce the correct correlation function fordetection by a second threshold detecting device 90. Referring to FIGS.1 and 8 (which illustrates the components of demodulating device 86),the demodulating device 86, like the correlating device 70 includes auser code generator 200, a projection builder 204, and a bank ofprojection filters 208. The projection builder 204 and bank ofprojection filters 208 use the equations set forth above to provideprojection operators and correlation functions. Unlike the correlatingdevice 70 which provides for a series of hypothetical projectionoperators and correlation functions based on the trial time, receivetime, and candidate symbol for each multipath signal segment, thedemodulating device 86 uses the “RAKED” sequence which has only a singlealigned signal segment rather than a plurality of independent multipathsignal segments. Accordingly, the demodulating device 86 is able toreliably estimate the actual transmit time for the source signal andtherefore requires considerably less processing to determine acorrelation function than the correlating device 70.

For each of the I and Q channels, the user code generator 200 in thedemodulating device 86 selects the user to decode for each alignedsignal segment, selects a transmit time and symbol for the alignedsignal segment and, for each transmit time and symbol, generates theuser or interference code for the selected user

The projection builder 204 selects a portion of the “RAKED” sequence toprocess, collects the pertinent user codes from the user code generator200, and, using the receive times, transmit times, and symbols, createsa series of projection operators for each aligned signal segment in the“RAKED” sequence.

Next, the bank of projection filters 208, with one filter correspondingto each pair of transmit times and symbols and therefore each projectionoperator, provides a set of filter outputs (e.g., correlation functions)each defining a second correlation surface to be threshold detected.

The second correlation surface is then detected by a second thresholddetecting device 90 to determine the actual transmit time and symbol foreach aligned signal. FIG. 9 depicts a representative correlation surface212 corresponding to a correlation function determined by one projectionfilter. Compared to the correlation surface 170 of FIG. 6, thecorrelation surface 212 has only a single peak 214 (due to the alignmentof the multipath signal segments in the “RAKED” sequence) as opposed tomultiple peaks.

Using the transmit time and symbol, the aligned signal segment can bedespread to provide the digital data for the aligned signal segmenttransmitted by each user.

Because the above-described system assumes that the interference fromother users is substantially the same for all multipath signal segmentsand/or that the amount of the interference in each multipath signalsegment is relatively small, the RAKE processor 82 and demodulatingdevice 86 require reconfiguration in applications where the interferencein each of the multipath signal segments is substantially different andthe interference is significant. To accommodate the differinginterference portions in each multipath signal segment, the user codegenerator 200, projection builder 204, and bank of projection filters208 process each multipath signal segment, corresponding to a peak inthe correlation surface, before the RAKE processor has aligned, scaled,and summed each of the multipath signal segments. After the interferenceportion of each multipath signal segment is removed by obliqueprojection techniques from that signal segment, the various multipathsignal segments can be aligned, scaled, and summed by the RAKE processoras set forth above. Alignment and scaling can be performed after obliqueprojection is completed as to a given multipath signal segment or afterall oblique projection is completed for all multipath signal segments.

Multiple Antenna Systems

FIG. 10 depicts a multiple antenna system according to anotherembodiment of the present invention. Each antenna 50 a-n is connected tofilters 250 a-n and 254 a-n, correlating device 258 a-n, thresholddetecting device 262 a-n, and a RAKE processor 266 a-n. The thresholddetecting devices 262 a-n for all of the antennas 50 a-n are connectedto a common timing reconciliation device 270, which in turn is connectedto all of the RAKE processors 266 a-n. In this manner, all of the RAKEprocessing for all of the filtered signals is performed relative to acommon reference time. The output of the RAKE processors 266 a-n isprovided to a common demodulating device 274 for determination of thecorrelation functions and summing of the signal portions received by allof the antennas that are attributable to a selected user. The system ineffect “phases” the output of each antenna in order to maximize the SNR.

As will be appreciated, the output of each antenna in a conventionalantenna array contains a desired signal but at a delay relative to theoutputs of the other antennas. The amount of relative delay is afunction of the arrangement of the antennas as well as the angularlocation of the source. Conventional beam-steering methods attempt tocompensate for this time delay so that the desired signals addconstructively thereby increasing the power of the desired signal. Ingeneral, an N antenna system can improve the SNR by a factor of N.

In the multiple antenna system of the present invention, by contrast,the compensation for the relative delays is performed in the RAKEprocessors 266 a-n. In order to accomplish this, the system sums theantenna outputs without compensating for the relative delays. Thecorrelation process may result in Np peaks as opposed to just pmultipath induced peaks. These Np peaks are then used to align and scalethe various signal segments prior to summation. The RAKE processor, ineffect, performs the phase-delay compensation usually done inbeam-steering.

The system architecture of the present invention thus does not requireknowledge of array geometries and steering vectors. It does not requireiterative searches for directions as is the case for systems that steerthe beam using techniques like LMS and its variants. Finally, it iscomputationally very efficient.

Referring to FIGS. 11-12, the software to operate the multiple antennasystem of FIG. 10 will now be described. The software detects spreadspectrum signals in the presence of interference from other users.

Initially, a channel is opened 278 to the respective antenna 50 a-n, anda user is selected 282 to demodulate the signal segments transmitted bythe selected user. The outputted spread spectrum signal of therespective antenna 50 a-n is converted 286 into the I and Q channels.The channels are filtered by the filters 250 a-n and 254 a-n to form thefiltered signals 290 a-n and 294 a-n. As will be appreciated, thefiltering operation is generally not performed in radar and GPSapplications.

Filtered signal portions are selected 298 for processing. In the querybox 302, if other users are present in the selected filtered signalportion, P^(⊥) _(s) is set 306 based on candidate interference codes. Ifnot, P^(⊥) _(s) is set 310 to I.

After the user is selected in box 282, trial times are generated 314 forthe selected user. Next, candidate user codes are generated 318 for eachof the trial times.

Next, hypothetical projection operators are created 322 for each trialtime and filtered signal portion to be processed. The filtered signalportion is correlated 326 by user with the trial time, receive time, andcandidate symbol to create the hypothetical correlation function. Thehypothetical correlation function characterizes the multipath signalsegments from the user of interest while nulling out the interferencefrom other known users.

A correlation surface is generated and thresholded 330 to identify peaksin the hypothetical correlation functions.

Based on the receive times for all multipath signal segments for a givensource signal received by each of the antennas, timing reconciliation334 is performed. The minimum receive time of all of the correspondingmultipath signal segments is selected as the reference time.

Based on the magnitudes of the peaks and the estimated receive times andthe reference time, RAKE processing 338 is performed on all of the datasegments.

The outputs from all of the RAKE processors 266 a-n are combined 342 toform a combined output 343.

Using the correct user codes and the correct interference codes, whichare provided by RAKE processing, projection operators are created 346for each data segment.

Based on the projection operators and the combined output, the alignedmultipath signals segments for all of the antennas are correlated 350and a second correlation surface generated.

Threshold detection 354 is performed to provide the digital data. Theabove-noted steps are repeated for other users and/or other multipathsignal segments.

Location Using Multiple Antenna System

The multiple antenna system of FIG. 10 can be utilized to locate thesource of a selected signal by triangulation. In case the multipleantennas on a base-station are evenly spaced, with spacing d, then thetime difference between when the first signal from the source impingeson any two antennas can be used to estimate direction of arrival of thesignal. This approach assumes that the first signal is a direct signalfrom the source. If θ is the angle to the source and t₀ is the timedelay from when the first signal hits the first antenna and then thesecond antenna, then the formula for computing θ is$\theta = {\sin^{- 1}\left( \frac{{ct}_{0}}{d} \right)}$

where

d-antenna spacing

c-speed of light

Using ranging protocols currently in base-stations, one can obtainestimates of range to the source. This range information either alone orin combination with angle estimates, when obtained from multiplebase-stations, can be processed using decentralized filtering algorithmsto get accurate location information about the source. The decentralizedfiltering algorithms are known. Examples of decentralized filteringalgorithms include decentralized Kalman filters and the Federatedfilter.

While various embodiments of the present invention have been describedin detail, it is apparent that modifications and adaptations of thoseembodiments will occur to those skilled in the art. However, it is to beexpressly understood that such modifications and adaptations are withinthe scope of the present invention, as set forth in the followingclaims.

What is claimed is:
 1. A system for receiving a signal, comprising: anantenna adapted to receive a signal, the signal being decomposable intoa first CDMA signal segment attributable to a first emitter; and obliqueprojecting means for determining the first CDMA signal segment, thefirst CDMA signal segment spanning a first signal space, the obliqueprojecting means being in communication with the antenna and determiningthe first CDMA signal segment by projecting obliquely a signal spacespanned by the signal onto the first signal space.
 2. The system ofclaim 1, wherein the signal is also decomposable into a second signalsegment attributable to an emitter other than the first emitter andwherein the signal space is obliquely projected onto the first signalspace along a projection space that is parallel to a second signal spacespanned by the second signal segment.
 3. The system of claim 1, whereinthe system includes: a) a plurality of antennas, each of which receivesat least a portion of the signal, and b) a corresponding plurality ofoblique projecting means in communication with the plurality ofantennas, each of the plurality of oblique projecting means beingadapted to determine by oblique projection the first CDMA signal segmentof the respective signal portion received by the corresponding antenna.4. The system of claim 3, including a corresponding plurality of RAKEprocessors in communication with the plurality of oblique projectingmeans, wherein each of the plurality of oblique projecting meansproduces a respective oblique projecting means output which is receivedas a RAKE processor input by each of the plurality of oblique projectingmeans' corresponding RAKE processor, the respective output of each ofthe plurality of oblique projecting means being delayed relative to oneanother, each of the plurality of RAKE processors being adapted to alignand scale its respective input to produce a compensated output.
 5. Thesystem of claim 4, wherein the compensated output of each of theplurality of RAKE processors is delivered to a summing correlator. 6.The system of claim 3, further comprising: a plurality of RAKEprocessing means, each RAKE processing means being in communication witha corresponding one of the plurality of oblique projecting means andproducing a corresponding aligned first signal attributable to the firstemitter; and a demodulating means, in communication with the pluralityof RAKE processing means, for demodulating at least a portion of eachcorresponding aligned first signal, the at least a portion of eachcorresponding aligned first signal defining a respective aligned firstspace, the demodulating means determining the corresponding alignedfirst signals by obliquely projecting a respective signal space definedby a corresponding aligned first signal onto the respective alignedfirst space.
 7. The system of claim 1, further including a RAKEprocessor having a RAKE input, wherein the oblique projecting meansproduces an oblique projecting means output which is coupled to the RAKEinput.
 8. The system of claim 1, wherein the first CDMA signal segmentcomprises a plurality of multipath signal segments and the obliqueprojecting means outputs a correlation function having a plurality ofpeaks corresponding to the plurality of multipath signal segments, andfurther comprising: threshold detecting means, in communication withthe,oblique projecting means, for generating timing information defininga temporal relationship among the plurality of peaks.
 9. The system ofclaim 8, wherein the system comprises a plurality of oblique projectingmeans and a plurality of antennas and wherein each of said antennas isin communication with a corresponding threshold detecting means andfurther comprising: timing reconciliation means for determining areference time based on timing information received from each of thethreshold detecting means.
 10. The system of claim 9, furthercomprising: a respective RAKE processing means, in communication witheach of the oblique projecting means and the timing reconciliationmeans, for aligning the plurality of multipath signal segments in atleast one of time and phase as a function of at least one of magnitudesof the plurality of multipath signal segments, the reference time, andthe phase, wherein the RAKE means outputs an aligned first signal.
 11. Asystem for receiving a signal, comprising: an antenna adapted to receivea signal and adapted to generate an output signal, the output signalbeing decomposable into: (i) a first CDMA signal portion attributable toa first source, and (ii) a noise portion, the noise portion having amagnitude; and, an oblique projection operator in communication with theantenna for determining the first CDMA signal portion of the outputsignal, the oblique projection operator determining the first CDMAsignal portion of the output signal using an equation that comprises thefollowing mathematical expression: (I−S(S ^(T) S)⁻¹ S ^(T))H(H^(T)(I−S(S ^(T) S)⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T)) whereinH is related to an interference code matrix of the first source, S isrelated to an interference code matrix of a second source, ^(T) denotesthe transpose operation, and I denotes the identity matrix.
 12. Thesystem of claim 11, wherein the antenna includes a receiver and at leasta portion of the noise portion is generated by the receiver.
 13. Thesystem of claim 11, wherein the system comprises a plurality of obliqueprojection operators corresponding to a plurality of antennas, each ofthe plurality of oblique projection operators being adapted to determinea respective first CDMA signal portion in a corresponding signalreceived by each of the plurality of antennas using the equation ofclaim
 11. 14. The system of claim 13, including a correspondingplurality of RAKE processors in communication with the plurality ofoblique projection operators, wherein each of the plurality of obliqueprojection operators produces a corresponding oblique projectionoperator output which is received as a RAKE processor input by itscorresponding RAKE processor, the corresponding oblique projectionoperator output of each of the plurality of oblique projection operatorsbeing delayed relative to one another, each of the plurality of RAKEprocessors being adapted to align and scale their respective inputs toproduce a corresponding compensated output.
 15. The system of claim 14,wherein the corresponding compensated output of each of the plurality ofRAKE processors is delivered to a second oblique projection operator incommunication therewith for determining a refined first CDMA signalportion in each of the compensated outputs using the equation of claim11.
 16. The system of claim 11, wherein the first CDMA signal portioncomprises a plurality of multipath signal segments and the obliqueprojection operator outputs a correlation function having a plurality ofpeaks corresponding to the plurality of multipath signal segments, andfurther comprising: a threshold detector, in communication with theoblique projection operator, for generating timing information defininga temporal relationship among the plurality of peaks.
 17. The system ofclaim 16, wherein the system comprises a plurality of antennas and aplurality of oblique projection operators in communication with acorresponding threshold detector and further comprising: a timingreconciliation device for determining a reference time based on timinginformation received from each of the threshold detectors.
 18. Thesystem of claim 17, further comprising: a corresponding plurality ofRAKE processors, in communication with the plurality of obliqueprojection operators and the timing reconciliation device, for aligningthe plurality of multipath signal segments in at least one of time andphase based on magnitudes of the plurality of multipath signal segmentsand the reference time to form an aligned first CDMA signal.
 19. Amethod for processing a composite signal, the method comprising thesteps of: (a) providing a composite signal that is decomposable into afirst CDMA signal portion that is attributable to a first emitter; and(b) obliquely projecting a signal space corresponding to the compositesignal onto a first signal space corresponding to the first CDMA signalportion to determine a parameter of the first CDMA signal portion. 20.The method of claim 19, wherein the composite signal is decomposableinto a second signal portion attributable to a second emitter other thanthe first emitter and wherein, in the obliquely projecting step, thesignal space is obliquely projected onto the first signal space along aprojection space that is parallel to a second signal space correspondingto the second signal portion.
 21. The method of claim 20, wherein theobliquely projecting step is performed according to the followingmathematical expression: (I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T)) where H is related to aninterference code matrix of the first emitter, S is related to aninterference code matrix of the second emitter, ^(T) denotes thetranspose operation, and I denotes the identity matrix.
 22. The methodof claim 19, wherein the composite signal includes a second CDMA signalportion attributable to a second emitter other than the first emitterand wherein the obliquely projecting step determines the magnitude ofthe first CDMA signal portion and wherein the first and second CDMAsignal portions are transmitted asynchronously.
 23. The method of claim22, further comprising: determining an actual time of transmission ofthe first CDMA signal portion; determining an actual received time forthe first CDMA signal portion; and repeating step (b) using the actualtime of transmission of the first CDMA signal portion and the actualreceived time.
 24. The method of claim 19, wherein the first CDMA signalportion comprises a plurality of multipath signal segments and furthercomprising: aligning at least one of a received time and phase of themultipath signal segments to produce an aligned first signal.
 25. Themethod of claim 24, further comprising: scaling the multipath signalsegments.
 26. The method of claim 19, wherein the first CDMA signalportion comprises a plurality of multipath signal segments, each of theplurality of multipath signal segments being received at differenttimes, and further comprising: assigning to a portion of each of theplurality of multipath signal segments a respective time of receipt. 27.The method of claim 26, further comprising: determining a reference timeof receipt based on the respective times of receipt.
 28. The method ofclaim 27, further comprising: first, summing the plurality of multipathsignal segments without regard to the differing times of receipt to forma summated peak magnitude; second, aligning the plurality of multipathsignal segments relative to the reference time of receipt to form aplurality of aligned signals; third, scaling each of the multipathsignal segments to form a plurality of scaled signals; and fourth,summing at least one of the aligned signals and the scaled signals. 29.A method for decomposing a composite signal having a first CDMA signalsegment attributable to a first emitter, comprising: obliquelyprojecting a signal space spanned by the composite signal onto a firstsignal space spanned by the first CDMA signal segment to determine aparameter of the first CDMA signal segment; and processing theparameter.
 30. The method of claim 29, wherein the composite signalincludes a second CDMA signal segment attributable to a second emitterother than the first emitter and wherein, in the obliquely projectingstep, the signal space is obliquely projected onto the first signalspace along a projection space that is parallel to a second signal spacespanned by the second CDMA signal segment.
 31. The method of claim 30,wherein the obliquely projecting step is performed according to thefollowing mathematical expression: (I−S(S ^(T) S)⁻¹ S ^(T))H(H^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T)) where His related to an interference code matrix of the first emitter, S isrelated to an interference code matrix of the second emitter, ^(T)denotes the transpose operation, and I denotes the identity matrix. 32.The method of claim 29, wherein the composite signal includes a secondCDMA signal segment attributable to a second emitter other than thefirst emitter and wherein the first and second CDMA signal segments aretransmitted asynchronously.
 33. The method of claim 29, wherein thefirst CDMA signal segment comprises a plurality of multipath signalsegments and further comprising: aligning at least one of a receivedtime and phase of the multipath signal segments to produce an alignedfirst signal.
 34. The method of claim 33, further comprising: scalingthe multipath signal segments.
 35. The method of claim 29, wherein thefirst CDMA signal segment comprises a plurality of multipath signalsegments, each of the plurality of multipath signal segments beingreceived at different times, and further comprising: assigning to aportion of each of the plurality of multipath signal segments arespective time of receipt.
 36. The method of claim 35, furthercomprising: determining a reference time of receipt based on therespective times of receipt.
 37. The method of claim 36, furthercomprising: first, summing the plurality of multipath signal segmentswithout regard to the differing times of receipt to form a summated peakmagnitude; second, aligning the plurality of multipath signal segmentsrelative to the reference time of receipt to form a plurality of alignedsignals; third, scaling each of the multipath signal segments to form aplurality of scaled signals; and fourth, summing at least one of thealigned signals and the scaled signals.
 38. The method of claim 29,further comprising: determining an actual time of transmission of thefirst CDMA signal segment; determining an actual received time for thefirst CDMA signal segment; and repeating the obliquely projecting stepusing the actual time of transmission of the first CDMA signal segmentand the actual received time.
 39. A system for processing an outputsignal of an antenna, comprising: an oblique projection operator thatdetermines a parameter of a selected signal component of an outputsignal of a receiving antenna, the selected signal component beingattributable to an emitter having an interference code matrix and theoblique projection operator determining a parameter of the selectedsignal component by projecting obliquely an output signal space spannedby the output signal onto a selected signal space spanned by theselected signal component.
 40. The system of claim 39, wherein theantenna includes a receiver and at least a portion of a noise portion ofthe output signal is generated by the receiver.
 41. The system of claim39, wherein the system comprises a plurality of oblique projectionoperators corresponding to a plurality of antennas and being incommunication therewith, each of the plurality of oblique projectionoperators being adapted to determine a respective selected signalcomponent of a corresponding portion of a respective composite signalreceived by each of the plurality of antennas and determine therespective selected signal component of the corresponding output signalusing an equation that includes the following mathematical expression:(I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T))H) ⁻¹ H^(T)(I−S(S ^(T) S ⁻¹)S ^(T)) where H is related to the interference codematrix of the emitter, S is related to an interference code matrix of asecond emitter, ^(T) denotes the transpose operation, and I denotes theidentity matrix.
 42. The system of claim 41, wherein the systemcomprises a plurality of RAKE processors corresponding to the pluralityof oblique projection operators, wherein each of the plurality ofoblique projection operators produces a corresponding oblique projectionoperator output which is received as a RAKE processor input by each ofthe plurality of oblique projection operator's corresponding RAKEprocessor, the corresponding oblique projection operator output of eachof the plurality of oblique projection operators being delayed relativeto one another, each of the plurality of RAKE processors being adaptedto align and scale their respective inputs to produce a correspondingcompensated output.
 43. The system of claim 42, wherein thecorresponding compensated output of each of the plurality of RAKEprocessors is delivered to a second oblique projection operator incommunication therewith for determining a refined oblique projectionoperator output of each of the compensated outputs using the equation ofclaim
 41. 44. The system of claim 39, wherein the selected signalcomponent comprises a plurality of multipath signal segments and theoblique projection operator outputs a correlation function having aplurality of peaks corresponding to the plurality of multipath signalsegments, and further comprising: a threshold detector, in communicationwith the oblique projection operator, for generating timing informationdefining a temporal relationship among the plurality of peaks.
 45. Thesystem of claim 44, wherein the system comprises a plurality ofantennas, each in communication with a corresponding threshold detectorand further comprising: a timing reconciliation device for determining areference time based on timing information received from each of thethreshold detectors.
 46. The system of claim 45, further comprising: aplurality of RAKE processors, in communication with a plurality ofoblique projection operators and the timing reconciliation device, foraligning the plurality of multipath signal segments in at least one oftime and phase based on magnitudes of the plurality of multipath signalsegments and the reference time to form an aligned first signal.
 47. Asystem for processing a plurality of output signals of a plurality ofantennas, the output signals being decomposable into a respectiveportion of a first coded signal component attributable to a first sourcehaving an interference code matrix, comprising: a plurality of obliqueprojection means, corresponding with the plurality of antennas and beingin communication therewith, for obliquely projecting a respective signalspace spanned by the respective output signal onto a respective firstsignal space spanned by the respective first coded signal component todetermine a parameter of the first coded signal component.
 48. Thesystem of claim 47, wherein at least one of the output signals isdecomposable into a second coded signal component, the second codedsignal component being attributable to a second source other than thefirst source and wherein the respective signal space is obliquelyprojected onto the respective first signal space along a projectionspace that is parallel to a second signal space corresponding to thesecond coded signal component.
 49. The system of claim 47, wherein thesystem comprises a plurality of RAKE processors corresponding with theplurality of oblique projection means, wherein each of the plurality ofoblique projection means produces a respective oblique projection meansoutput which is received as a RAKE processor input by each of theplurality of oblique projection means' corresponding RAKE processor, therespective output of each of the plurality of oblique projection meansbeing delayed relative to one another, each of the plurality of RAKEprocessors being adapted to align and scale its respective input toproduce a compensated output.
 50. The system of claim 49, wherein thecompensated output of each of the plurality of RAKE processors isdelivered to a summing correlator.
 51. The system of claim 47, wherein afirst oblique projection comprises a plurality of multipath signalsegments and at least one of the plurality of oblique projection meansoutputs a correlation function having a plurality of peaks correspondingto the plurality of multipath signal segments, and further comprising:threshold detection means, in communication with the at least oneoblique projection means, for generating timing information defining atemporal relationship among the plurality of peaks.
 52. The system ofclaim 51, further comprising: timing reconciliation means fordetermining a reference time based on timing information received fromthe threshold detection means.
 53. The system of claim 52, furthercomprising: a plurality of RAKE processing means, wherein a respectiveRAKE processing means is in communication with each of the plurality ofoblique projecting means and the timing reconciliation means, foraligning the plurality of multipath signal segments in at least one oftime and phase as a function of at least one of the magnitudes of theplurality of multipath signal segments, the reference time, and thephase, each RAKE processing means outputting a corresponding alignedfirst signal.
 54. The system of claim 53, further comprising: ademodulating means, in communication with the plurality of RAKEprocessing means, for demodulating at least a portion of eachcorresponding aligned first signal, the at least a portion of eachcorresponding aligned first signal defining a respective aligned firstspace, the demodulating means determining the corresponding alignedfirst signals by obliquely projecting a respective signal space definedby a corresponding aligned first signal onto the respective alignedfirst space.
 55. A coded signal processor, comprising: a plurality ofoblique projection operators in communication with a correspondingplurality of antennas, each of the plurality of oblique projectionoperators projecting a corresponding composite signal space spanned by arespective composite coded signal output by the corresponding antennaonto a corresponding first signal space spanned by a respective firstsignal component of the respective composite coded signal along acorresponding projection space that is parallel to a correspondingsecond signal space spanned by at least a respective second signalcomponent of the respective composite coded signal to determine acorresponding parameter of the respective first signal component,wherein the projection of the corresponding composite signal space ontothe corresponding first signal space along the corresponding projectionspace is performed in accordance with the following mathematicalexpression: (I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S^(T))H)⁻¹ H ^(T)(I−S(S ^(T) S ⁻¹)S ^(T) where H is related to aninterference code matrix of a first emitter associated with therespective first signal component, S is related to an interference codematrix of a second emitter associated with the respective second signalcomponent, ^(T) denotes the transpose operation, and I denotes theidentity matrix.
 56. The coded signal processor of claim 55, wherein thecorresponding parameter is a time offset.
 57. The coded signal processorof claim 55, wherein at least a portion of a noise portion of therespective composite coded signal is generated by a receiver.
 58. Thecoded signal processor of claim 55, comprising a corresponding pluralityof RAKE processors in communication with the plurality of obliqueprojection operators, wherein each of the plurality of obliqueprojection operators produces a corresponding oblique projectionoperator output which is received as a RAKE processor input by eachoblique projection operator's corresponding RAKE processor, thecorresponding oblique projection operator output of each of theplurality of oblique projection operators being delayed relative to oneanother, each of the plurality of RAKE processors being adapted to alignand scale their respective inputs to produce a corresponding compensatedoutput.
 59. The coded signal processor of claim 58, wherein thecorresponding compensated output of each of the plurality of RAKEprocessors is delivered to a second oblique projection operator incommunication therewith for determining a refined oblique projectionoperator output corresponding to the compensated outputs using theequation of claim
 55. 60. A method for processing a composite signal,comprising: projecting a first composite signal space spanned by a firstcomposite coded signal onto a first signal space spanned by a firstsignal component of the first composite coded signal along a projectionspace parallel to a first interference space spanned by a second signalcomponent of the first composite coded signal to determine a parameterof the first signal component, wherein the first signal component isattributable to at least a first emitter and the second signal componentis attributable to at least a second emitter other than the at least afirst emitter.
 61. The method of claim 60, wherein the method determinesa parameter and the parameter is a time offset.
 62. The method of claim60, wherein the first and second signal components are transmittedasynchronously.
 63. The method of claim 60, wherein the first signalcomponent comprises a plurality of multipath signal segments and furthercomprising: aligning at least one of a received time and phase of themultipath signal segments to produce an aligned first signal.
 64. Themethod of claim 60, further comprising: determining an actual time oftransmission of the first signal component; determining an actualreceived time for the first signal component; and repeating theprojecting step using the actual time of transmission of the firstsignal component and the actual received time.
 65. The method of claim60, wherein the projecting step is performed according to an equationthat includes the following mathematical expression: (I−S(S ^(T) S)⁻¹ S^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T) S)⁻¹ S^(T)) where H is related to an interference code matrix of the at leasta first emitter, S is related to an interference code matrix of the atleast a second emitter, ^(T) denotes the transpose operation, and Idenotes the identity matrix.
 66. A method for processing a compositesignal, comprising: projecting a first composite signal space spanned bya first composite coded signal onto a first signal space spanned by afirst signal component of the first composite coded signal along aprojection space parallel to a first interference space spanned by asecond signal component of the first composite coded signal to determinea parameter of the first signal component, wherein the first sgianlcomponent is atrtibuatable to at least a first emitter and the secondsignal component is attribuatable to at least a second emitter otherthan the at least a first emitter.
 67. The method of claim 66, whereinthe first signal component is attributable to a first emitter, and thecoded signal includes at least a second signal component attributable toat least a second emitter different from the first emitter.
 68. Themethod of claim 67, wherein at least a portion of the projecting step isperformed according to the following mathematical expression: (I−S(S^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T)S)⁻¹ S ^(T)), where H is related to an interference code matrix of thefirst emitter, S is related to an interference code matrix of the atleast a second emitter, ^(T) denotes the transpose operation, and Idenotes the identity matrix.
 69. The method of claim 66, wherein thefirst signal component is attributable to a first emitter, the codedsignal includes at least a second signal component attributable to atleast a second emitter other than the first emitter and wherein thefirst and second signal components are transmitted asynchronously. 70.The method of claim 66, wherein the first signal component comprises aplurality of multipath signal segments and further comprising: aligningat least one of a received time and phase of the multipath signalsegments to produce an aligned first signal.
 71. The method of claim 70,further comprising: scaling the multipath signal segments.
 72. Themethod of claim 66, wherein the first signal component comprises aplurality of multipath signal segments, each of the plurality ofmultipath signal segments being received at different times, and furthercomprising: assigning to a portion of each of the plurality of multipathsignal segments a respective time of receipt.
 73. The method of claim66, further comprising: determining an actual time of transmission ofthe first signal component; determining an actual received time for thefirst signal component; and repeating the projecting step using theactual time of transmission of the first signal component and the actualreceived time.
 74. A system for receiving a signal, comprising: anantenna adapted to receive a signal, the signal being decomposable intoa first coded signal segment attributable to a first emitter; obliqueprojecting means for determining the first coded signal segment, thefirst coded signal segment spanning a first signal space, the obliqueprojecting means being in communication with the antenna and determiningthe first coded signal segment by projecting obliquely a signal spacespanned by the signal onto the first signal space; and a RAKE processorhaving a RAKE input, wherein the oblique projecting means produces anoblique projecting means output which is coupled to the RAKE input. 75.The system of claim 74, further comprising: second oblique projectingmeans for determining, based on the output of the RAKE processor, atransmit time and symbol for a first coded signal corresponding to thefirst coded signal segment; and decoding means for decoding the firstcoded signal based on the transmit time and symbol.
 76. A system forreceiving a signal, comprising: an antenna adapted to receive a signal,the signal being decomposable into a first coded signal segmentattributable to a first emitter; oblique projecting means fordetermining the first coded signal segment, the first coded signalsegment spanning a first signal space, the oblique projecting meansbeing in communication with the antenna and determining the first codedsignal segment by projecting obliquely a signal space spanned by thesignal onto the first signal space, wherein the first coded signalsegment comprises a plurality of multipath signal segments and theoblique projecting means outputs a correlation function having aplurality of peaks corresponding to the plurality of multipath signalsegments; and threshold detecting means, in communication with theoblique projecting means, for generating timing information defining atemporal relationship among the plurality of peaks.
 77. A method forprocessing a composite signal, the method comprising the steps of: (a)providing at least one composite signal that is decomposable into atleast a first coded signal portion that is attributable to a firstemitter; (b) obliquely projecting at least one signal spacecorresponding to the at least one composite signal onto at least a firstsignal space corresponding to the at least a first coded signal portionto determine at least one parameter of the at least a first coded signalportion, wherein the at least a first coded signal portion comprises aplurality of multipath signal segments; and (c) aligning at least one ofa received time and phase of the multipath signal segments to produce analigned first signal.
 78. The method of claim 77, further comprising:(d) selecting a trial transmit time and candidate symbol for the alignedfirst signal; (e) generating a candidate interference code correspondingto the aligned first signal; (f) determining a projection operatorcorresponding to the aligned first signal; (g) generating a correlationfunction corresponding to the aligned first signal; (h) determining atleast one of a transmit time and symbol for the aligned first signal;and (i) based on the at least one of a determined transmit time and thedetermined symbol, decoding the aligned first signal.
 79. The method ofclaim 77, wherein step (b) comprises: selecting a candidate symbol. andtrial time corresponding to the first coded signal portion; generating acandidate interference code corresponding to the first coded signalportion; determining a hypothetical projection operator corresponding tothe first coded signal portion; generating a hypothetical correlationfunction corresponding to the first coded signal portion; and detectinga peak in the hypothetical correlation function to provide timinginformation used in the aligning step.
 80. A method for processing acomposite signal, the method comprising the steps of: (a) providing atleast one composite signal that is decomposable into at least a firstcoded signal portion that is attributable to a first emitter; (b)obliquely projecting at least one signal space corresponding to the atleast one composite signal onto at least a first signal spacecorresponding to the at least a first coded signal portion to determineat least one parameter of the at least a first coded signal portion,wherein the at least a first coded signal portion comprises a pluralityof multipath signal segments, each of the plurality of multipath signalsegments being received at different times; and (c) assigning to atleast a portion of the plurality of multipath signal segments arespective time of receipt.
 81. A method for decomposing a compositesignal having a first coded signal segment attributable to a firstemitter, comprising: obliquely projecting a signal space spanned by thecomposite signal onto a first signal space spanned by the first codedsignal segment to determine at least one parameter of the first codedsignal segment; processing the parameter, wherein the first coded signalsegment comprises a plurality of multipath signal segments; and aligningat least one of a received time and phase of the multipath signalsegments to produce an aligned first signal.
 82. A method fordecomposing a composite signal having a first coded signal segmentattributable to a first emitter, comprising: obliquely projecting asignal space spanned by the composite signal onto a first signal spacespanned by the first coded signal segment to determine at least oneparameter of the first coded signal segment; processing the parameter;determining a time of transmission of the first coded signal segment;determining a received time for the first coded signal segment; andrepeating the obliquely projecting step using the time of transmissionand the received time of the first coded signal segment.
 83. A systemfor processing an output signal of an antenna, comprising: an obliqueprojection operator that determines at least one parameter of a selectedsignal component of an output signal of an antenna, the selected signalcomponent being attributable to an emitter having an interference codematrix and the oblique projection operator determining at least oneparameter of the selected signal component by projecting obliquely anoutput signal space spanned by the output signal onto a selected signalspace spanned by the selected signal component to form an obliqueprojection of the output signal space on the selected signal space,wherein the oblique projection comprises a plurality of multipath signalsegments and the oblique projection operator outputs a correlationfunction having a plurality of peaks corresponding to the plurality ofmultipath signal segments; and a threshold detector, in communicationwith the oblique projection operator, for generating timing informationdefining a temporal relationship among the plurality of peaks.
 84. Thesystem of claim 83, further composing: a RAKE processor that uses thetiming information to align and scale the selected signal component toprovide a RAKE output; a correlator that determines a correlationfunction based on the RAKE output; a second threshold detector thatdetermines, based on the correlation function, a transmit time andsymbol for the RAKE output; and a decoder that decodes a selected signalcorresponding to the selected signal component using the transmit timeand symbol.
 85. A system for processing an output signal of an antenna,the output signal being decomposable into a first coded signal componentattributable to a first source having an interference code matrix,comprising: oblique projection means for obliquely projecting a signalspace spanned by the output signal onto a first signal space spanned bythe first coded signal component to determine at least one parameter ofthe first coded signal component; and a RAKE processor having a RAKEinput, wherein the oblique projection means produces an obliqueprojection means output which is coupled to the RAKE input.
 86. Thesystem of claim 85, wherein the oblique projecting means outputs acorrelation function having a plurality of peaks and further comprising:a first threshold detector that generates timing information defining atemporal relationship among the plurality of peaks, wherein the timinginformation is in the oblique projection means output; a correlator thatdetermines a correlation function based on the output of the RAKEprocessor; a second treshold detector that determines, based on thecorrelation function, a transmit time and symbol for the RAKE output;and a decoder that decodes a selected signal corresponding to the firstcoded signal component using the transmit time and symbol.
 87. A methodfor processing a composite signal, the method comprising the steps of:(a) providing a composite signal that is decomposable into a first codedsignal portion that is attributable to a first emitter; and (b)obliquely projecting a signal space corresponding to the compositesignal onto a first signal space corresponding to the first coded signalportion to determine at least one parameter of the first coded signalportion, wherein the composite signal is decomposable into a secondsignal portion attributable to a second emitter other than the firstemitter, wherein, in the obliquely projecting step, the signal space isobliquely projected onto the first signal space along a projection spacethat is parallel to a second signal space corresponding to the secondsignal portion, and wherein at least a portion of the obliquelyprojecting step is performed according to the following mathematicalexpression: (I−S(S ^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S^(T))H)⁻¹ H ^(T)(I−S(S ^(T) S)⁻¹ S ^(T)), where H is related to aninterference code matrix of the first emitter, S is related to aninterference code matrix of the second emitter, ^(T) denotes thetranspose operation, and I denotes the identity matrix.
 88. A method fordecomposing a composite signal having a first coded signal segmentattributable to a first emitter, comprising: obliquely projecting asignal space spanned by the composite signal onto a first signal spacespanned by the first coded signal segment to determine at least oneparameter of the first coded signal segment; and processing theparameter, wherein the composite signal includes a second coded signalsegment attributable to a second emitter other than the first emitter,wherein, in the obliquely projecting step, the signal space is obliquelyprojected onto the first signal space along a projection space that isparallel to a second signal space spanned by the second coded signalsegment, and wherein at least a portion of the obliquely projecting stepis performed according to the following mathematical expression: (I−S(S^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T)S)⁻¹ S ^(T)) where H is related to an interference code matrix of thefirst emitter, S is related to an interference code matrix of the secondemitter, ^(T) denotes the transpose operation, and I denotes theidentity matrix.
 89. A coded signal processor, comprising: at least afirst oblique projection operator that projects at least one compositesignal space spanned by a composite coded signal onto at least a firstsignal space spanned by at least a first signal component of thecomposite coded signal along at least one projection space that isparallel to at least a second signal space spanned by at least a secondsignal component of the composite coded signal to determine at least oneparameter of the at least a first signal component, wherein the at leasta first signal component comprises a plurality of multipath signalsegments and the first oblique projection operator outputs a correlationfunction having a plurality of peaks corresponding to the plurality ofmultipath signal segments; and a threshold detector, in communicationwith the first oblique projection operator, for generating timinginformation defining a temporal relationship among the plurality ofpeaks.
 90. The coded signal processor of claim 89, wherein the codedsignal processor is in communication with a plurality of antennas andcomprises a plurality of threshold detectors, wherein a thresholddetector corresponds to each antenna and further comprising: a timingreconciliation device for determining a reference time based on timinginformation received from each of the threshold detectors.
 91. The codedsignal processor of claim 90, wherein the at least a first obliqueprojection operator comprises a plurality of oblique projectionoperators and further comprising: a corresponding plurality of RAKEprocessors, in communication with the oblique projection operators andthe timing reconciliation device, for aligning the plurality ofmultipath signal segments in at least one of time and phase based onmagnitudes of the plurality of multipath signal segments and thereference time to form an aligned first signal.
 92. The coded signalprocessor of claim 89, further comprising: a RAKE processor that usesthe timing information to align and scale the at least a first signalcomponent to provide a RAKE output; a correlator that determines acorrelation function based on the RAKE output; a second thresholddetector that determines, based on the correlation function, a transmittime and symbol for the RAKE output; and a decoder that decodes a firstsignal corresponding to the at least a first signal component using thetransmit time and symbol.
 93. A coded signal processor, comprising: atleast a first oblique projection operator that projects a compositesignal space spanned by a composite coded signal onto a first signalspace spanned by a first signal component in the composite coded signalalong a projection space that is parallel to a second signal spacespanned by at least a second signal component in the composite codedsignal to determine at least one parameter of the first signalcomponent; an antenna; and a receiver in communication with the antennaand the at least a first oblique projection operator, wherein thecomposite coded signal comprises noise and at least a portion of thenoise is generated by the receiver.
 94. The coded signal processor ofclaim 93, further comprising: a first correlator that determines ahypothetical correlation function corresponding to the first signalcomponent; a first threshold detector that determines, based on thehypothetical correlation function, timing information related to thefirst signal component; a RAKE processor that uses the timinginformation to align and scale the first signal component to provide aRAKE output; a second correlator that determines a correlation functionbased on the RAKE output; a second threshold detector that determines,based on the. correlation function, a transmit time and symbol for theRAKE output; and a decoder that decodes a first signal corresponding tothe first signal component using the transmit time and symbol.
 95. Acoded signal processor, comprising: at least a first oblique projectionoperator that projects a composite signal space spanned by a compositecoded signal onto a first signal space spanned by a first signalcomponent in the composite coded signal along a projection space that isparallel to a second signal space spanned by at least a second signalcomponent in the composite coded signal to determine at least oneparameter of the first signal component, wherein the parameter is a timeoffset.
 96. The coded signal processor of claim 95, further comprising:a first correlator that determines a hypothetical correlation functioncorresponding to the first signal component; a first threshold detectorthat determines, based on the hypothetical correlation function, timinginformation related to the first signal component; a RAKE processor thatuses the timing information to align and scale the first signalcomponent to provide a RAKE output; a second correlator that determinesa correlation function based on the RAKE output; a second thresholddetector that determines, based on the correlation function, a transmittime and symbol for the RAKE output; and a decoder that decodes a firstsignal corresponding to the first signal component using the transmittime and symbol.
 97. A method for processing a composite signal,comprising: projecting a first composite signal space spanned by a firstcomposite coded signal onto a first signal space spanned by a firstsignal component of the first composite coded signal along a projectionspace that is parallel to at least a second interference space spannedby at least a second signal component of the first composite codedsignal to determine at least one parameter of the first signalcomponent, wherein the parameter is a time offset.
 98. The method ofclaim 97, further comprising: aligning and scaling the first signalcomponent to form an aligned first signal; selecting a first transmittime and symbol for the aligned first signal; generating an interferencecode corresponding to the aligned first signal; determining a projectionoperator corresponding to the aligned first signal; generating acorrelation function corresponding to the aligned first signal;determining at least one of a second transmit time and symbol for thealigned first signal; and based on the at least one of a second transmittime and symbol, decoding the aligned first signal.
 99. A method forprocessing a composite signal, comprising: projecting a first compositesignal space spanned by a first composite coded signal onto a firstsignal space spanned by a first signal component of the first compositecoded signal along a projection space that is parallel to at least asecond interference space spanned by at least a second signal componentof the first composite coded signal to determine at least one parameterof the first signal component, wherein the first signal component isattributable to at least a first emitter and the at least a secondsignal component is attributable to at least a second emitter other thanthe first emitter and wherein the first and second signal components aretransmitted asynchronously.
 100. The method of claim 99, wherein theprojecting step comprises: selecting a candidate symbol and trial timecorresponding to the first signal component; generating a candidateinterference code corresponding to the first signal component;determining a hypothetical projection operator corresponding to thefirst signal component; generating a hypothetical correlation functioncorresponding to the first signal component; and threshold detecting thehypothetical correlation function to determine temporal locations of aplurality of peaks.
 101. The method of claim 99, further comprising:aligning and scaling the first signal component to form an aligned firstsignal; selecting a first transmit time and symbol for the aligned firstsignal; generating an interference code corresponding to the alignedfirst signal; determining a projection operator corresponding to thealigned first signal; generating a correlation function corresponding tothe aligned first signal; determining at least one of a second transmittime and symbol for the aligned first signal; and using the at least oneof a second transmit time and symbol, decoding the aligned first signal.102. A method for processing a composite signal, comprising: projectingat least a first composite signal space spanned by at least a firstcomposite coded signal onto at least a first signal space spanned by atleast a first signal component of the at least a first composite codedsignal along at least one projection space that is parallel to at leasta second interference space spanned by at least a second signalcomponent in the first composite coded signal to determine at least oneparameter of the at least a first signal component, wherein the at leasta first signal component comprises a plurality of multipath signalsegments; and aligning at least one of a received time and phase of themultipath signal segments to produce an aligned first signal.
 103. Themethod of claim 102, further comprising: scaling the multipath signalsegments.
 104. The method of claim 102, wherein each of the plurality ofmultipath signal segments was received at different times, and furthercomprising: assigning to a portion of each of the plurality of multipathsignal segments a respective time of receipt.
 105. The method of claim104, further comprising: determining a reference time of receipt basedon the respective times of receipt.
 106. The method of claim 105,further comprising: first, summing the plurality of multipath signalsegments without regard to the differing times of receipt to form asummated peak magnitude; second, aligning the plurality of multipathsignal segments relative to the reference time of receipt to form aplurality of aligned signals; third, scaling each of the multipathsignal segments to form a plurality of scaled signals; and fourth,summing at least one of the aligned signals and the scaled signals. 107.The method of claim 102, wherein the projecting step comprises:selecting a candidate symbol and trial time corresponding to the atleast a first signal component; generating a candidate interference codecorresponding to the at least a first signal component; determining ahypothetical projection operator corresponding to the at least a firstsignal component; generating a hypothetical correlation functioncorresponding to the at least a first signal component; and thresholddetecting the hypothetical correlation function to determine temporallocations of a plurality of peaks.
 108. The method of claim 102, furthercomprising: selecting a first transmit time and symbol for the alignedfirst signal; generating an interference code corresponding to thealigned first signal; determining a projection operator corresponding tothe aligned first signal; generating a correlation functioncorresponding to the aligned first signal; determining at least one of asecond transmit time and symbol for the aligned first signal; and usingthe at least one of a second transmit time and symbol, decoding thealigned first signal.
 109. A method for processing a composite signal,comprising: projecting at least a first composite signal space spannedby at least a first composite coded signal onto at least a first signalspace spanned by at least a first signal component of the at least afirst composite coded signal along at least one projection space that isparallel to at least a first interference space spanned by at least asecond signal component of the at least a first composite coded signalto determine at least one parameter of the at least a first signalcomponent, wherein the at least a first signal component comprises aplurality of multipath signal segments, each of the plurality ofmultipath signal segments being received at different times; andassigning to at least one of the plurality of multipath signal segmentsa respective time of receipt.
 110. The method of claim 109, wherein theprojecting step comprises: selecting a candidate symbol and trial timecorresponding to the at least a first signal component; generating acandidate interference code corresponding to the at least a first signalcomponent; determining a hypothetical projection operator correspondingto the at least a first signal component; generating a hypotheticalcorrelation function corresponding to the at least a first signalcomponent; and threshold detecting the hypothetical correlation functionto determine temporal locations of a plurality of peaks.
 111. The methodof claim 109, further comprising: aligning and scaling the at least afirst signal component to form an aligned first signal; selecting afirst transmit time and symbol for the aligned first signal; generatingan interference code corresponding to the aligned first signal;determining a projection operator corresponding to the aligned firstsignal; generating a correlation function corresponding to the alignedfirst signal; determining at least one of a second transmit time andsymbol for the aligned first signal; and based on the at least one of asecond transmit time and symbol, decoding the aligned first signal. 112.A method for processing a composite signal, comprising: projecting afirst composite signal space spanned by a first composite coded signalonto a first signal space spanned by a first signal component of thefirst composite coded signal along a projection space that is parallelto at least a first interference space spanned by at least a secondsignal component of the first composite coded signal to determine atleast one parameter of the first signal component; determining a time oftransmission of the first signal component; determining a received timefor the first signal component; and repeating the projecting step usingthe time of transmission and the received time of the first signalcomponent.
 113. The method of claim 112, wherein the projecting stepcomprises: selecting a candidate symbol and trial time corresponding tothe first signal component; generating a candidate interference codecorresponding to the first signal component; determining a hypotheticalprojection operator corresponding to the first signal component;generating a hypothetical correlation function corresponding to thefirst signal component; and threshold detecting the hypotheticalcorrelation function to determine temporal locations of a plurality ofpeaks.
 114. The method of claim 112, wherein the projecting stepcomprises: selecting a first symbol and first transmit timecorresponding to the first signal component; generating a firstcandidate interference code corresponding to the first signal component;determining a first hypothetical projection operator corresponding tothe first signal component; generating a first hypothetical correlationfunction corresponding to the first signal component; and thresholddetecting the first hypothetical correlation function to determinetemporal locations of a plurality of peaks.
 115. A method for processinga coded signal, the coded signal being decomposable into at least afirst signal component, comprising: projecting obliquely at least onesignal space spanned by the coded signal onto at least a first signalspace spanned by the at least a first signal component to determine atleast one parameter of the at least a first signal component, whereinthe at least a first signal component comprises a plurality of multipathsignal segments; and aligning at least one of a received time and phaseof the multipath signal segments to produce an aligned first signal.116. The method of claim 115, further comprising: selecting a firsttransmit time and symbol for the aligned first signal; generating aninterference code corresponding to the aligned first signal; determininga projection operator corresponding to the aligned first signal;generating a correlation function corresponding to the aligned firstsignal; determining at least one of a second transmit time and symbolfor the aligned first signal; and based on the at least one of a secondtransmit time and symbol, decoding the aligned first signal.
 117. Themethod of claim 115, wherein the projecting step comprises: selecting acandidate symbol and trial time corresponding to the at least a firstsignal component; generating a candidate interference code correspondingto the at least a first signal component; generating a candidateinterference code corresponding to the at least a first signalcomponent; determining a hypothetical projection operator correspondingto the at least a first signal component; generating a hypotheticalcorrelation function corresponding to the at least a first signalcomponent; and threshold detecting the hypothetical correlation functionto determine the temporal locations of a plurality of peals.
 118. Amethod for processing a coded signal, the coded signal beingdecomposable into at least a first signal component, comprising:projecting obliquely at least one signal space spanned by the codedsignal onto at least a first signal space spanned by the at least afirst signal component to determine at least one parameter of the atleast a first signal component, wherein the at least a first signalcomponent comprises a plurality of multipath signal segments; andscaling the multipath signal segments.
 119. The method of claim 118,further comprising: aligning the multipath signal segments to form analigned first signal; selecting a first transmit time and symbol for thealigned first signal; generating an interference code corresponding tothe aligned first signal; determining a projection operatorcorresponding to the aligned first signal; generating a correlationfunction corresponding to the aligned first signal; determining at leastone of a second transmit time and symbol for the aligned first signal;and using the at least one of a second transmit time and symbol,decoding the aligned first signal.
 120. A method for processing at leastone coded signal, the at least one coded signal being decomposable intoat least a first signal component, comprising: projecting obliquely atleast one signal space spanned by the at least one coded signal onto atleast a first signal space spanned by the at least a first signalcomponent to determine at least one parameter of the at least a firstsignal component, wherein the at least a first signal componentcomprises a plurality of multipath signal segments, each of theplurality of multipath signal segments being received at differenttimes; and assigning to at least one of the plurality of multipathsignal segments a respective time of receipt.
 121. The method of claim120, further comprising: determining a reference time of receipt basedon the at least one assigned respective time of receipt.
 122. The methodof claim 121, further comprising: first, summing the plurality ofmultipath signal segments without regard to the differing times ofreceipt to form a summated peak magnitude; second, aligning theplurality of multipath signal segments relative to the reference time ofreceipt to form a plurality of aligned signals; third, scaling each ofthe multipath signal segments to form a plurality of scaled signals; andfourth, summing at least one of the aligned signals and the scaledsignals.
 123. The method of claim 120, wherein the projecting stepcomprises: selecting a candidate symbol and trial time corresponding tothe at least a first signal component; generating a candidateinterference code corresponding to the at least a first signalcomponent; determining a hypothetical projection operator correspondingto the at least a first signal component; generating a hypotheticalcorrelation function corresponding to the at least a first signalcomponent; and threshold detecting the hypothetical correlation functionto detemine temporal locations of a plurality of peaks.
 124. A methodfor processing a coded signal, the coded signal being decomposable intoat least a first signal component, comprising: projecting obliquely asignal space spanned by the coded signal onto a first signal spacespanned by the first signal component to determine at least oneparameter of the first signal component; determining a time oftransmission of the first signal component; determining a received timeof the first signal component; and repeating the projecting step usingat least one of the time of transmission and the received time.
 125. Themethod of claim 124, further comprising: aligning and scaling the firstsignal component to form an aligned first signal; selecting a firstsymbol for the aligned first signal; generating an interference codecorresponding to the aligned first signal; determining a projectionoperator corresponding to the aligned first signal; generating acorrelation function corresponding to the aligned first signal;determining a second transmit time and symbol for the aligned firstsignal; and using the at least one of a second transmit time and symbol,decoding the aligned first signal.
 126. The method of claim 124, whereinthe projecting step comprises: selecting a candidate symbol and trialtime corresponding to the first signal component; generating a candidateinterference code corresponding to the first signal component;determining a hypothetical projection operator corresponding to thefirst signal component; generating a hypothetical correlation functioncorresponding to the first signal component; and threshold detecting thehypothetical correlation function to determine temporal locations of aplurality of peaks.
 127. A method for processing a coded signal, thecoded signal being decomposable into at least a first signal component,comprising: projecting obliquely a signal space spanned by the codedsignal onto a first signal space spanned by the first signal componentto determine at least one parameter of the first signal component,wherein the first signal component is attributable to a first emitter,wherein the coded signal includes at least a second signal componentattributable to at least a second emitter different from the firstemitter, and wherein at least a portion of the projecting step isperformed according to the following mathematical expression: (I−S(S^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T)S)⁻¹ S ^(T)), where H is related to an interference code matrix of thefirst emitter, S is related to an interference code matrix of the atleast a second emitter, ^(T) denotes the transpose operation, and Idenotes the identity matrix.
 128. The method of claim 127, furthercomprising: aligning and scaling the first signal component to form analigned first signal; selecting a transmit time and symbol for thealigned first signal; generating an interference code corresponding tothe aligned first signal; determining a projection operatorcorresponding to the aligned first signal; generating a correlationfunction corresponding to the aligned first signal; determining at leastone of a transmit time and symbol for the aligned first signal; andusing the at least one of a transmit time and symbol, decoding thealigned first signal.
 129. The method of claim 127, wherein theprojecting step comprises: selecting a candidate symbol and trial timecorresponding to the first signal component; generating a candidateinterference code corresponding to the first signal component;determining a hypothetical projection operator corresponding to thefirst signal component; generating a hypothetical correlation functioncorresponding to the first signal component; and threshold detecting thehypothetical correlation function to determine temporal locations of aplurality of peaks.
 130. A system for receiving a signal, comprising: aplurality of antennas each of which is adapted to receive a respectivesignal, each respective signal being decomposable into a respectivefirst coded signal segment attributable to a first emitter; and acorresponding plurality of oblique projecting means for determining therespective first coded signal segment, the respective first coded signalsegment spanning a corresponding first signal space, the plurality ofoblique projecting means being in communication with the correspondingplurality of antennas and each of the plurality of oblique projectingmeans determining the respective first coded signal segment byprojecting obliquely onto the corresponding first signal space acorresponding signal space spanned by the respective signal received bythe corresponding antenna.
 131. The system of claim 130, wherein atleast one of the respective signals is also decomposable into a secondsignal segment attributable to an emitter other than the first emitterand wherein the corresponding signal space spanned by the respectivesignal is obliquely projected onto the corresponding first signal spacealong a corresponding projection space that is parallel to a secondsignal space spanned by the second signal segment.
 132. The system ofclaim 130, including a corresponding plurality of RAKE processors incommunication with the plurality of oblique projecting means, whereineach of the plurality of oblique projecting means produces a respectiveoblique projecting means output which is received as a RAKE processorinput by each of the plurality of oblique projecting means'corresponding RAKE processor, the respective output of each of theplurality of oblique projecting means being delayed relative to oneanother, each of the plurality of RAKE processors being adapted to alignand scale its respective input to produce a compensated output.
 133. Thesystem of claim 132, wherein the compensated output of each of theplurality of RAKE processors is delivered to a summing correlator. 134.The system of claim 130, further comprising: a plurality of RAKEprocessing means, each RAKE processing means being in communication witha corresponding one of the plurality of oblique projecting means andproducing a corresponding aligned first signal attributable to the firstemitter; and a demodulating means, in communication with the pluralityof RAKE processing means, for demodulating at least a portion of eachcorresponding aligned first signal, the at least a portion of eachcorresponding aligned first signal defining a respective aligned firstspace, the demodulating means determining the corresponding alignedfirst signals by obliquely projecting a respective signal space definedby a corresponding aligned first signal onto the respective alignedfirst space.
 135. A method for processing a composite signal, the methodcomprising the steps of: (a) providing a composite signal that isdecomposable into a first coded signal portion that is attributable to afirst emitter; and, (b) obliquely projecting a signal spacecorresponding to the composite signal onto a first signal spacecorresponding to the first coded signal portion to determine a parameterof the first coded signal portion, wherein the composite signal includesa second coded signal portion attributable to a second emitter otherthan the first emitter, wherein the obliquely projecting step determinesthe magnitude of the first coded signal portion and wherein the firstand second coded signal portions are transmitted asynchronously. 136.The method of claim 135, wherein, in the obliquely projecting step, thesignal space is obliquely projected onto the first signal space along aprojection space that is parallel to a second signal space correspondingto the second coded signal portion.
 137. A method for decomposing acomposite signal having a first coded signal segment attributable to afirst emitter, comprising: obliquely projecting a signal space spannedby the composite signal onto a first signal space spanned by the firstcoded signal segment to determine a parameter of the first coded signalsegment; and processing the parameter, wherein the composite signalincludes a second coded signal segment attributable to a second emitterother than the first emitter and wherein the first and second codedsignal segments are transmitted asynchronously.
 138. The method of claim137, wherein, in the obliquely projecting step, the signal space isobliquely projected onto the first signal space along a projection spacethat is parallel to a second signal space spanned by the second codedsignal segment.
 139. A system for processing an output signal of anantenna, comprising: a plurality of oblique projection operators,corresponding to a plurality of antennas and being in communicationtherewith, each projection operator determining a respective signalcomponent of a respective output signal of the corresponding antenna,the respective signal component being attributable to an emitter havingan interference code matrix and each oblique projection operatordetermining a parameter of the respective signal component by projectingobliquely a signal space spanned by the respective output signal onto asignal space spanned by the respective signal component using anequation that includes the following mathematical expression: (I−S(S^(T) S)⁻¹ S ^(T))H(H ^(T)(I−S(S ^(T) S) ⁻¹ S ^(T))H)⁻¹ H ^(T)(I−S(S ^(T)S)⁻¹ S ^(T)) where H is related to an interference code matrix of theemitter, S is related to an interference code matrix of a secondemitter, ^(T) denotes the transpose operation, and I denotes theidentity matrix.
 140. The system of claim 139, wherein at least aportion of a respective noise portion of the respective output signal isgenerated by a receiver.
 141. The system of claim 139, wherein thesystem comprises a plurality of RAKE processors corresponding to theplurality of oblique projection operators, wherein each of the pluralityof oblique projection operators produces a corresponding obliqueprojection operator output which is received as a RAKE processor inputby each of the plurality of oblique projection operator's correspondingRAKE processor, the corresponding oblique projection operator output ofeach of the plurality of oblique projection operators being delayedrelative to one another, each of the plurality of RAKE processors beingadapted to align and scale their respective inputs to produce acorresponding compensated output.
 142. The system of claim 141, whereinthe corresponding compensated output of each of the plurality of RAKEprocessors is delivered to a second oblique projection operator incommunication therewith for determining a refined oblique projectionoperator of each of the compensated outputs using the equation of claim139.